Silva, a £24million summer signing from Valencia, confessed that City have only themselves to blame.
He told The Sun: "We have failed in key moments of the season and United have really profited.
"We've dropped points in games where it was obligatory to win. I don't analyse the behaviour of team-mates but Carlos and Mario are the main men here.
"We need them in attack and their absence has been noticed.
"Their future depends on Roberto Mancini and the club. People speak about inexperience but I think absences, injuries and our own anxiety have motivated United's rise."